Aircraft interconnecting mechanism



Dec. 22, 1953 c. J. LEISY AIRCRAFT INTERCONNECTING MECHANISM 5 Sheets-Sheet 1 Filed Aug. 2, 1949 INVENTOR. CLIFFORD J. LEISY ATTORNEYS Dec. 22, 1953 c, LElsY AIRCRAFT INTERCONNECTING MECHANISM 3 Sheets-Sheet 2 Filed Aug. 2, 1949 INVENTOR. CLIFFORD J? LE/SY ATTORNEYS Dec. 22, 1953 c. J. LEISY AIRCRAFT INTERCONNECTING MECHANISM 5 Sheets-Sheet 3 Filed Aug. 2, 1949 .Dlllllllllllll AvI illlllllllllllllllll.

INVENTOR. CLIFFORD J. LE/SY ATTORNEYS effected aerodynamically.

Patented Dec. 22, 1953 UN I TED S TATE S FATE-N T F- F'I CE ensaszs AIRCRAFT INTERCONNE'CTING MECHANISM Clifford J. Leisy, Seattle, Wash, assiignor' to-Bo'eing Airplane Company, Seattle, Wash, amorporation' of Delaware Application August .2, 1949;Serial No. '108;07'0

:21 Claims. "1

'Thisinventionmelates to apparatus for transferring ,fuel from one airplane to another while "in flight, and incorporates cooperating mechanism on the'tan'ker airplane a'nd on the receiving airplane. While reference will be rnade herein principally to the use of such apparatus 'for portion of the apparatu's'carried'bythe receiving airplane without the necessity o'f'any crewmemher in the latter exposingany'portion of his body to the air stream.

A further important"advanta'geof the apparatus is'the rapidity and facility with which the cooperating'parts of the apparatus on the tanker airplane and on the receiving airplane may be brought into contact and'connected together to accomplish the refueling operation most 'expeditiously, which is of great importance particularly for military aircraft because the airplanes are more vulnerable to attack when in refueling relationship because of their close proximity and lack of maneuverability. Another object is toenable'the refueling operation to be effected when the airplanes are traveling athigh speeds, and because the entire operation of "refueling may be carried out relatively quickly, ordinarily it can be accomplished without the receiving airplane departing from the course 'of its mission, so that no appreciable "delay in its flight occurs. The possibility of damage to the receiving airplane is further minimized because of the control over the fuel tra'nsferring'c'onduit which is afforded.

'More specifically, 'itis an object of the invention to form the fuel transferring conduit as a telescoping boom supported upon the tanker airplane by one end and swingable universally, so that its trailing end may be shifted quickly fore and aft, to the right or to "the left, and up or down as may be necessary to effect connection of its swinging end with the 'complemental portion of the refueling apparatus carried by the receiver airplane. Appropriate swinging of the boom is controlled by an operator in the tanker airplane, and preferably such manipulation is 'To facilitate inter- -connection of the b'o'om and the receiving air- "pl'ane conduit, ifprefer ably the latter is formed :as a socket provide'd'with appropriate guide ways "for guiding movement of the swinging end of the boom from the vicinity of such socket into proper -seating engagement with it.

Additional features of the invention include safety mechanism for controlling the flow of fuel through the boom 'conduitprior to completion of operating engagement between the complemental parts of the apparatus and subsequent to disconnection of them. Means positively connecting the itankerairplane and a'portion-of the boom "between its ends is operative to limit excessive swinging of the boom -and'to swing the boom iii-to stored position. The same means may hold the boom in *thatposition at times other than during :the' refuelihg operation, and particularly while the tanker airplane is taking off from the airport or landing.

Advantages of particular details of therefueling mechanism, inad'dition to the general advantages and "objects mentioned above, are pointed outin'the following particular description of the exemplaryform of'apparatus shown in the drawmgs.

Figure 1 :is a side elevation vie'v'v'of the stern portion of "a tanker airplane andthe bow portion of a receiving airplane, showing the boom condui't'interconhe'cting the two airplanes, andillustrating in broken linespermissible variations in altitude of the receiving .plane relative to the tanker airpla'rieduring the refueling operation.

Figure 2is arplan view of the stern. portion of a tanker airplanea'nd the bow portion of a receiving airplane, showing the boom conduit interconnecting them, and in broken lines showing laterally displaced .positions of 'the receiving 1 airplane relative to the tanker airplane which may be -assumeol-during the refueling operation.

Figure Sis a top perspective view of the stern :portion of a't'ank'er airplaneand the bow .portion :of 5a receiving airplane with the boom conduit interconnecting the tWo.

Figure '4 is a top perspective View of the stern portion of a tanker airplane, showing details of the boom supporting and controlling mechanism, and Figure 5 is a fragmentary top perspective view with parts broken away of the control mounting.

Figure '6 is a longitudinal section through the coor -andl i'gure 'Tis' a transverse section, showing onet'ype of operating mechanism foreffecting b'oom telescoping, and Figure 8 is a detail longit'udirial"section view throughthe nozzle.

strain on the boom mechanism.

Figure 9 is a longitudinal section through a portion of the boom, the remainder being in side elevation,

In refueling operations previous to the advent of my development it has been customary to use a flexible hose draped between the tanker airplane and the receiving airplane. Such hose has been difficult to connect between the tanker and receiving airplane, and even after such connection, while dangling from the tanker airplane, has been largely uncontrollable. Various plans have been proposed for the receiving airplane to contact such a flexible hose, but all or them are rather uncertain and consume considerable time to accomplish.

The present development utilizes a rigid conduit in the form of a boom adjustable in efiective length, such. as by incorporating a plurality of telescoping rigid tube sections. Such a boom I, as shown in Figure 1, is attached by its leading end to the tanker airplane '1, preferably near its stern, and in fuel transferring position is inclined rearwardly and downwardly from the tanker airplane. To avoid subjecting the boom to large bending loads its position is not controlled by mechanism exerting a force on its anchored end, but instead the position of the booms trailing end is controlled by air reaction surfaces 2 carried by the boom at a. location remote from its anchored end and preferably at or near the trailing end of the boom. lhe entire directional control of the boom can be effected by such control surfaces, thus enabling the forward end of the boom to be pivoted freely for universal movement,

As shown in Figures 1, 2 and 3, it is desirable for such a boom l to be swingable through a sufficient amplitude relative to the tanker airplane, both laterally and vertically, and to be sufficiently adjustable in eifective length, so that th tanker airplane T and. the receiving airplane R may move relatively through a reasonable range during the refueling operation without placing any If these airplanes tend to shift relatively more than allowed by the mounting of the booms anchored end, the swinging end of such boom will be disconnected automatically from the receiving airplane, so that i even in that case no unexpected load will be placed on the fuel transfer mechanism.

When the receiving airplane R moves vertically relative to the tanker airplane T, as shown in Figure l, the boom I must not only be swung through an angle about a horizontal axis, but i must be altered in eifective length if the fore and aft positions of the airplanes do not change, in

i order to maintain the connection of the swinging end of boom with the receiving airplane. For that reason the boom is composed of a plurality of telescoping sections, the construction illustrated including an inner tube IE3 slidably received within the principal tubular member I l of move relatively laterally, as indicated in Figure 2, the eifective length of the boom must change if the relative fore and aft locations of the airplanes and their relative elevations are not changed.

To enable the boom to swing in the manner discussed above, the anchored end of its section ii is carried by a universal joint on the tanker airplane encircling the supported end of the tube H, as shown best in Figures 6 and 9. The universal joint is of conventional ginibal ring type, so that the supported end of tube 3 i is fully open internally for passage of fuel through it or reception of a flexible fuel-carrying conduit 3 received within it and extending therefrom through the tube it. Potentiometers It, associated with the pivots of the universal joint l2 disposed in vertical and horizontal planes, respectively, may be appropriately connected to indicators so that a crew member of the tanker airplane may be advised at all times as to the angular disposition of the boom relative to the airplane, both vertically and athwartships of the airplane.

As mentioned previously, it is preferred that no bending load be placed on the boom by attempting to control its swinging by the application of a force to it near or forward or its universal'joint mounting 12. The air reaction control surfaces 2 utilized to exert a swinging or defiecting force on the boom are therefore mounted on the boom a substantial distanc rearwardly from its anchored end, and preferably as close as possible to the trailing end of the principal boom section l l.

The boom air reaction surfaces 2 may include stationary and swingable empennage surfaces corresponding to those used conventionally on airplanes. Thus they may comprise a vertical fin 2t and a rudder 2i hin 'edly connected to the trailing edge of the vertical fin, which operate to produce directional.stabilizing and control forces. The rudder may be deflected relative to the fin to swing the trailing end of the boom from side to side by manipulation of usual control cables 23 suitably connected to horns on the rudder shown in Figure 9. ihe vertical location of the booms swinging end may be controlled and maintained by elevators 2t mounted on a pivot shaft 25 extending through the main boom section i l, and which may be swung by control cables 25 in a manner similar to the movement of elevators on an airplane.

The rudder control cables 23 and the elevator control cables as preferably are housed in streamlined cowling i i extending upward, from the tube H for the purpose of protecting from the air stream such cables and other operating mechanism to be described. From the forward end of such cowling the control cables extend alongside universal joint 52 into the tanker airplane, and thence to a control station shown in Figure 4.

The rudder control cables 23 and the elevator control cables 26 pas upwardly from tube member H around guide pulleys 2? carried by the airplane slightly above the universal joint l2. From these guide pulleys the elevator control cables 23 extend rear-weirdly around a pair of guide pulleysfie and thence upwardly about an actuating drum i carried by a shaft it extending longitudinally of the airplane. Through the end of this shaft remote from wheel 4 extends a crosspin ll journaled in a spherical mounting member 42, shown in Figure 5. This mounting member is held in sockets formed in the adjacent faces of brackets l3 projecting downward from the roof of the airplane fuselage in generally parallel relationship.

The elevator control cables '26 extend upwardly from the guide pulleys 2? over a pair of guide pulleys 29, and thence rearwardly alongside shaft to locations respectively :above and the mounting ball 12, shown in Figure f1. Integral with this ball element is an upright lever M having holes 4 5 or suitable attachment fittings with which the cables 25 may be connected approximatelye ual distances above and below'tthe ba l-Hi2. The lower end of lever -44 may beiformed as a handle, and, as shown in Figure '4, is supported in a location alongside the right shoulder of an operator 0 by the ball 32 held between brackets 43. i

If the operator "shifts the lower end of the lever a l athwartships or the airplane, ball 32 will "be rotated in its supporting brackets is generallyabout the ax'isof shaft til. :Suc'h movement will tilt about the same axis pin il anchored in the ball, which in turn will rotate shaft All, and hence drum 4, to reel in one stretch of cable 23 and correspondingly to 'pay out th other stretch, which will result in swinging of the boom rudder 2! through an angle corresponding to the displacement of the cable lever M. Preferably the vertical stretches of cables 23 are crossed prior to passing around drum l as shown in Figure 4, V so that as the lower end of lever 44 is swun to port, for example, the starboard horizontal stretch of cable 23 will be shortened and the port horizontal stretch will be payed out. Such cable movement will swing the rudder 2-1 to starboard, resulting in deflection of the trailing end of the boom l to port. With the cable 23 thus rigged, movement of the lower end of lever i l 'to port will therefore produce deflection of the swinging end of the boom to port, whereas deflection of the lower end of lever 6 to starboard will efiect swinging of the booms trailing end to starboard.

The lever M maybe swung through a considerable angle fore and aft without hindranc by shaft 4!! because there is considerable clearance between such shaft and the aperture in ball 32 through which it passes, as shown in Figure 5. During such movement the ball will simply pivot about pin 4], or such pin will pivot .in shaft 40. Movement of the lower end of lever id rearwardlv will shorten the lower stretch .of cable 26 in the fuselage, which corresponds to the upper stretch of the cable within the boom section H.

Such shortening; of the upper stretch of cable 7 of the lever ie is swung forward, the upper stretch of cable 26 in the airplane fuselage, and

hence the lower stretch in the boom section 1 i. will be shortened to tilt the elevator downward, eiiecting liftin of the trailing end of the boom.

It will be evident that by manipulation of the lever 64% in varying degrees, as described, the boom may be swung upward or downward and sidew'ise to any extent desired :at the will of the operator. Moreover, because of the universal movement of which ball &2 is capable, the handle on the lower end of control lever it may be moved universally generally in a horizontal plane .to shoot any combination of lateral and elevational movement of the booms trailing end. Indicators connected to the potentiometers l3 associated with the universaljoint 1'2 supporting the anchored end of the boom may be located alongside the operator '0 to apprise him of the angular disposition .of the boom both laterally and. vertically. Also, the operator preferably is able to the movement or the 'boom through :a 'vvindow 'Win'ithe bottom of the fuselage.

it desirable :Eor :the operator of the boom not only to have non'trol over its swinging move- 'ment, but also to be able to vary its effective length at will, by moving positively lengthwise the inner :tubular element It which telescopes within the section ll. vSuch movement of tube 1 0,maytberefiected'bya motordrive or by hydraulic piston mechanism. As shown in Figures 6 and .7, a, :motor drive may shift fore and aft a lug 5 projecting outward through a slot '50 in the wall of tube H covered by the fairing M. This lug is secured to a cable loop 5| which passes around a drive pulley irietionally engaging a worm gear '52 meshing with a 'worm b3, .ShOWIl best -in Fig. '7. Such worrn'may be rotated 'bv-a suitable reversible motor 54, which maybe either electric, hydrau'licor :air operated. Alternatively "the lug :5 maybe shifted by a suitable :air or hydraulic piston and cylinder arrangement. The end of the cableloop 5! remote from. motor is passes about a guide pulley 55.

To limit relative lengthwise movement of tubes I0 and H and to cushion interruption of such relative movement at limiting positions, tube ll may have :an inwardly projecting shoulder 15 near its trailing end, and tube it may have outwardly projecting shoulders spaced apart slightly farther than the total possible change in effective length of the boom, one, Iii, .at its outer end and another, ll, remote from its outer end. Between shoulders l5 and 15 is lodged .a helical compression spring 13 encircling tube and between shoulders 15 and H is lodged .a helical compression spring 19, also encircling tube It.

These springs are relatively short, and as the 'innertube ill approaches its limiting position of inward movement, spring 18 will be engaged by shoulders t, which will press .it against shoulder I 5 to cushion and interrupt inward movement of'thetube til. Conversely, as tube it nears the 'limitof its-extension movement, shoulder i! will synthetic rubber, to serve .as the fuel-carrying conduit.

This hose is adjustable in effective length axially through the tubes ii and it they are moved relatively lengthwise to alter the length :of the hollow boom. The rearward end of this-hose maybe suitably/connected to a rigid nozzle 36 received in the trailing end of the inner conduit section it. Limited longitudinal movement' between thenozzle 3t and the tube iii, may be afiorded, to absorb the shock on contact of the nozzle with its socket on the receiving airplane, by providing an external annular shoulder 3| on the nozzle and an internal annular shoulder 32 near the trailing end of tube it, between which shoulders is interposed a helical compression spring 33 received within tube iii and encircling the nozzle. The hose '3 will exert an inwardly acting force on nozzle which will be yieldingly resisted by spring 33.

The "tip portion .34 of the nozzle preferably is secured to the nozzle proper by a crosspi-n uni- 7 versal joint 35, the details of which construction are shown best in Fig. 8. The fuel passage through the nozzle is sealed about this universal joint by a metallic flexible tube 36 of the corrugated type, the ends of which are bonded to the nozzle body 33 and nozzle tip 3%, respectively.

The nozzle tip 3:3 preferably terminates in the head 31, which is tapered to fit in a suitable socket in receiving airplane R. Also, such tip may house a spring-pressed shut-off valve 33, which may be opened either automatically or voluntarily when the nozzle tip head 31 has been properly engaged in the socket of the receiving airplane.

Alternatively, a single-acting drive mechanism may be employed, merely to move tube 50 into tube H, and the hydraulic pressure of the liquid fuel within the boom may be relied upon to'exert a projecting force on tube it, as shown in Figure 9. The principal boom section H has an inwardly projecting sealing shoulder l5 near its trailing end, provided with a suitable sealing gasket contacting the outer surface of the tube Ill. Such latter tube carries an outwardly projecting annular shoulder ll at its forward end, likewise provided with a sealing gasket engaging the inner surface of tube section ii.

As in the form of device previously described,

a, helical compression cushioning spring 19 encircling the tube section lt is interposed between the annular shoulders l5 and H. Also, a helical compression spring it encircling the inner tube i9 is interposed between the shoulder l5 and a further shoulder 56', projecting outwardly from tube IE and located near its trailing end.

Because of the sealing gasket in the shoulder l I, the inner fuel-carrying flexible conduit 3 may be omitted, and instead the fuel may pass through a flexible hose section 39, preferably metallic, directly into the forward end of conduit section i l to which such hose section is connected. From tube section H the fuel passes into the inner tube H), which is connected by a universal joint and flexible tubing section 36 to the nozzle, as

previously described, and as shown in Figure 8. 4

With this type of apparatus it is not necessary to provide double-acting mechanism for shifting tube section i8 relative to tube section II to increase the effective length of the boom, because the pressure of the fuel in the conduit, pressing against the interior of the nozzle head closed by valve will exert a force which can be utilized to extend the boom. Such extending movement will be interrupted by engagement of shoulder ll with spring E9 to press such spring against ,1

the shoulder 55. Retraction of tube It may be effected by supplying hydraulic liquid under pressure to the chamber formed between the ribs 15' and H. Such hydraulic liquid will be confined between these ribs by their gaskets. The pressure of such liquid reacting against rib l5 will press on rib l? to shift tube it to the left in Figure 9, thereby retracting it to any desired extent into the tube ll.

Whatever type of drive mechanism is selected, it may be controlled by a control handle 55, shown in Figure 4 as disposed adjacent to the left hand of the operator (3. As this handle is shifted rearwardly the inner tube It may be extended, and as the handle is pulled forward the tube it may be retracted into tube H. Such handle would control the motor 5 in the mechanism shown in Figures 5 and 7. Where mechanism like that shown in Figure 9 is employed, the handle may be utilized to control the flow of liquid through conduit '51, either for the purpose of supplying liquid to effect retraction of tube ID, or to release such liquid so that the pressure of the fuel within the boom can force shoulder ll toward shoulder to extend the boom and at the same time to force hydraulic liquid from the chamber I?) back to the conduit 51' to a reservoir of the hydraulic liquid pres sure source (not shown).

In order to enable the extensible boom to be moved quickly and positively into stored position and to hold it in such position, a winch 6, shown in Figure 4, may be provided in the extreme tail of the tanker airplane T, which controls a cable 68. This cable is attached to a point on the boom section II located directly under the winch, by any suitable fitting such as the eye 6!. This eye is located sufiiciently far rearwardly of the universal joint l2 as to enable substantial leverage about the booms pivot to be exerted on the boom, but the trailing end of the boom should not project rearward so far beyond the eye 6! as to produce an objectionable bending stress in the boom when the cable till is tensioned.

In a typical refueling operation the receiving airplane R will be maneuvered into a position slightly behind and somewhat below the tail of the tanker airplane T, while the latter is held on a steady course. When the operator 0 sees the receiving airplane in approximately the correct position, viewed through his window W, for contact by the flying boom, he will release the winch 6 so that the cable 6t will run free, allowing the trailing end of the boom l to swing downward and to be controlled by the air reaction surfaces 2. The operator will then move lever it laterally and fore and aft as necessary to move the rudder 2i and elevators M, respectively, for swinging the trailing end of the boom to align it with the boom socket in the receiving airplane.

When the receiving airplane has assumed approximately its correct position with respect to the tanker airplane T for refueling and such formation has been reasonably stabilized, the operator will manipulate boom extension control handle 56 as necessary to project the inner section {U of the boom rearwardly from theouter section until contact is made with the receiving airplane. As shown best in Figure 3, preferably the receiving airplane has converging guide plates l disposedat opposite sides of the socl-ret for guiding contact by the head 31 of the flying boom, and the operator 0 will control the rudder 2i and elevators 26 while varying the eilective length of the boom to slide the head 3? of the boom along the surface of the fuselage of the receiving airplane between the plates 7 until the boom head has been lodged in its socket.

When the head 3? of the flying boom has been fitted into its socket on the receiving airplane, suitable latch means may be provided to secure the head in such position, or at least to hold it against minor forces tending to displace it, and valve 33 may be shifted to open position either by the coupling operation or subsequent to it.

After the tanker airplane and the receiving airplane have thus been interconnected for re fueling, lever 44 should be released by the operator '0 so that the rudder 2i and the elevators 24 may feather into alignment with the air stream, irrespective of relative vertical or eral movement of the airplanes. They will therefore not exert any force on the boom during the refueling operation which would produce any stress in it or tend to dislodge the head 3'5 of the 3 i erable to shift the after end of said boom toward and away from said air reaction control surfaces for interconnection with such other aircraft.

10. The combination defined in claim 9, in which the boom includes an outer tube on which the air reaction control surfaces are mounted and an inner tube telescoping within and projectable behind said outer tube, the universal joint means swingably supporting one end of saidouter tube from the aircraft.

11. In combination, a first aircraft and mechanism for interconnecting said first aircraft with another aircraft while in flight, said mechanism comprising a boom adjustable in effective length and having an aft end engageable with such other aircraft, universal joint means carried by said first aircraft, connected to the forward portion of said boom and swingably supporting said boom in position trailing from said first aircraft; control means independent of such other aircraft extending from said first aircraft past said universal joint means adjacent thereto and along said boom but stopping short of the aft end thereof and operable to effect universal swinging of said boom relative to said first aircraft, and means controllable from within said first aircraft and operable to adjust the effective length of said boom for interconnection with such other aircraft.

12. The combination defined in claim 11, in which the boom includes an outer tube and an inner member telescoping within said outer tube, the universal joint means swingably supporting one end of said outer tube from the first aircraft, and the control means stopping short of the aft end of said outer tube.

13. In combination, a first aircraft and mechanism for interconnecting said first aircraft with another aircraft while in flight, said mechanism comprising a boom having an aft end engageable with such other aircraft, universal joint means carried by said first aircraft, connected to the forward portion of said boom and swingably supporting said boom in position trailing from said first aircraft, and control means independent of such other aircraft extending from said first aircraft past said universal joint means adjacent thereto and along said boom but stopping short of the aft end thereof and operable to effect universal swinging of said boom relative to said first aircraft.

14. The combination defined in claim 13, and air reaction control surfaces independent of such other aircraft and carried by the boom at a location forward of its aft end, the control means a being operatively connected to said air reaction control surfaces, and movable to adjust such surfaces relative to the boom for effecting universal swinging of the boom.

15. In combination, an aircraft and mechanism for interconnecting said aircraft with another aircraft while in flight, said mechanism comprising a telescoping boom including an outer tube and an inner member, universal joint means carried by said aircraft and swingably supporting one end of the outer tube of said boom, air reaction control surfaces mounted on the other end of the outer tube of said boom, and means operatively connected to said air reaction control surfaces and movable from within said aircraft to adjust said surfaces for effecting universal swinging of said boom.

16. In combination, an aircraft and mechanism for interconnecting said aircraft with another aircraft while in flight, said mechanism comprising a telescoping boom including an outer' tube and an inner member, universal joint means carried by said aircraft and swingably supporting one end of the outer tube of said boom, air reaction control surfaces mounted on the other end of the outer tube of said boom, means operatively connected to said air reaction control surfaces and movable from within said aircraft to adjust said surfaces for effecting universal swinging of said boom, and means operable to project said inner member rearwardly from said outer tube.

17. Mechanism for interconnecting aircraft in flight, comprising a boom adapted to be mounted on an aircraft and including an outer tube and an inner member received in said outer tube and slidable lengthwise thereof, means operatively connected to said inner member and operable to slide it lengthwise of said outer tube, resilient means carried by said outer tube and received within it, and abutments carried by said inner member exteriorly thereof and adjacent to opposite ends thereof, respectively, engageable with said resilient means in extreme extended and extreme retracted positions of said inner member relative to said outer tube, respectively, to cushion movement of said inner member as it approaches its extreme positions of movement relative to said outer tube.

18. In combination, an aircraft and mechanism for interconnecting said aircraft with another aircraft while in flight, said mechanism comprising a boom, means carried by the under side of said aircraft forward of its rearward end and swingably supporting said boom from said'aircraft to dispose said boom in downward'and rearward trailingv attitude, and hoisting means carried by said aircraft at a location rearwardly ofsaid supporting means and bridging between such location and a portion of said boom outside the aircraft and rearwardly of and remote from said supporting means, and operable to swing the rearward end of said boom upwardly to dispose said boom in stored position close beneath and generally parallel to the lower surface of such aircraft.

19. The combination defined in claim '18, in

which the aircraft is an airplane and the hoisting means includes a winch housed within the airplane fuselage, and a cable extending through the fuselage Wall end depending from substantially the extreme aft end of the fuselage and interconnecting the boom and said winch.

20. The combination defined in claim 18, in which the boom includes an outer tube and an inner tube telescoping within said outer tube and projectable rearwardly therefrom to adjust the effective length of the boom, the hoisting means being connected to said outer tube.

21. Mechanism for interconnecting aircraft in flight comprising a boom adapted to be mounted on an aircraft and having an aft end. engageable with another aircraft, air reaction control surfaces carried by said boom at a location forward of its aft end and projecting from opposite sides of said boom, and pivot means supporting from said boom the end of each of said air reaction control surfaces adjacent to said boom for pivoting of each air reaction control surface about an axis extending spanwise of the respective air reaction control surface.

CLIFFORD J. LEISY.

(References on following page) 13 References Cited in the file of this patent Number UNITED STATES PATENTS Number Name Date 2:402283 1,544,032 POtBZ June 30, 1925 5 2 433 473 1,728,449 Procofiefi et a1. Sept. 17, 1929 1,729,354 Mounce Sept. 24, 1929 1,806,834 Ullendorff May 26, 1931 Number 1,818,834 Zimmerman Aug. 11, 1981 346,181 1,848,372 Moran Mar. 8, 1932 w Name Date Gilbert Nov. 16, 1943 Van Dusen Sept. 25, 1945 Hewitt June 18, 1946 Mitchell Dec. 30, 1947 FOREIGN PATENTS Country Date Great Britain Apr. 9, 1931 

